Search

Car manufacturers relentlessly replace or augment the functionality of mechanical subsystems with electronic components. Most such subsystems (e.g., steer-by-wire) are safety related, hence, subject to regulation. ISO-26262, the dominant standard for road vehicles, regards software faults as systematic, while differentiating hardware faults between systematic and random. The analysis of systematic faults entails rigorous processes and qualitative considerations. The increasing complexity of modern on-board computers, however, questions the very notion of treating the violation of execution-time envelopes for software programs as a systematic fault. Modern hardware in fact reduces the user's ability to delve deep enough into the fabric of hardware-software interaction to gage its extent of contribution to the worst-case execution time (WCET). Changing the nature of the WCET-analysis problem may help address that challenge effectively. To this end, we propose a solution that should allow ISO-26262 to quantify the likelihood of execution-time exceedance events, relating it to target failure metrics employed in support of certification arguments, similarly to random faults in hardware. To this end, we inject randomization in the timing behavior of the computer hardware to relieve the user from the need to control hard-to-reach low-level parts, and use measurement-based probabilistic timing analysis to quantify, constructively, the failure rates resulting from the likelihood of execution-time exceedance events.

Background: Despite considerable efforts made in recent years, the industrial accident rate and the fatality rate in the Republic of Korea are much higher than those in most developed countries in Europe and North America. Industrial safety policies and safety regulations are also known to be ineffective and inefficient in some cases. Methods: This study focuses on the quantitative evaluation of the effectiveness of direct safety regulations such as safety certification, self-declaration of conformity, and safety inspection of industrial machines in the Republic of Korea. Implications on safety policies to restructure the industrial safety system associated with industrial machines are also explored. Results: Analysis of causes in industrial accidents associated with industrial machines confirms that technical causes need to be resolved to reduce both the frequency and the severity of such industrial accidents. Statistical analysis also confirms that the indirect effects of safety device regulation on users are limited for a variety of reasons. Safety device regulation needs to be shifted to complement safety certification and self-declaration of conformity for more balanced direct regulations on manufacturers and users. An example of cost-benefit analysis on conveyor justifies such a transition. Conclusion: Industrial safety policies and regulations associated with industrial machines must be directed towards eliminating the sources of danger at the stage of danger creation, thereby securing the safe industrial machines. Safety inspection further secures the safety of workers at the stage of danger use. The overall balance between such safety regulations is achieved by proper distribution of industrial machines subject to such regulations and the intensity of each regulation. Rearrangement of industrial machines subject to safety certification and self-declaration of conformity to include more movable industrial machines and other industrial machines with a high level of danger is also suggested.

We present a metamodel for the specification of safety compliance needs.The metamodel abstracts concepts and criteria from different safety standards.Its application results in models for structuring and managing compliance information.It can be used for most critical computer-based and software-intensive systems. Context: Many critical systems must comply with safety standards as a way of providing assurance that they do not pose undue risks to people, property, or the environment. Safety compliance is a very demanding activity, as the standards can consist of hundreds of pages and practitioners typically have to show the fulfilment of thousands of safety-related criteria. Furthermore, the text of the standards can be ambiguous, inconsistent, and hard to understand, making it difficult to determine how to effectively structure and manage safety compliance information. These issues become even more challenging when a system is intended to be reused in another application domain with different applicable standards.Objective: This paper aims to resolve these issues by providing a metamodel for the specification of safety compliance needs for critical systems.Method: The metamodel is holistic and generic, and abstracts common concepts for demonstrating safety compliance from different standards and application domains. Its application results in the specification of "reference assurance frameworks" for safety-critical systems, which correspond to a model of the safety criteria of a given standard. For validating the metamodel with safety standards, parts of several standards have been modelled by both academic and industry personnel, and other standards have been analysed. We further augment this with feedback from practitioners, including feedback during a workshop.Results: The results from the validation show that the metamodel can be used to specify safety compliance needs for aerospace, automotive, avionics, defence, healthcare, machinery, maritime, oil and gas, process industry, railway, and robotics. Practitioners consider that the metamodel can meet their needs and find benefits in its use.Conclusion: The metamodel supports the specification of safety compliance needs for most critical computer-based and software-intensive systems. The resulting models can provide an effective means of structuring and managing safety compliance information.

OBJECTIVES: The aim of this study was to evaluate if safety certification reduces the risk of work injury among experienced manual tree-fallers. METHODS: This study used a retrospective cohort study design. Experienced manual tree-fallers employed in the Canadian province of British Columbia (N=3251) between 2003-2008 were enumerated from a mandatory faller registry. Registry records with demographic and certification data were linked to workers' compensation claims for injury outcomes. Data were analyzed using discrete time survival analysis over a two-year period, centered on certification date with pre- and post-certification demarcated into four three-month periods. Models were adjusted for demographic, occupation/industry, previous injury, and seasonal/temporal effects. RESULTS: The relative risk (RR) of work injury during the post certification periods were elevated in comparison to the pre-certification reference period, but the 95% confidence intervals included "1" for all estimates by the end of follow-up, suggesting no statistically significant increased risk of injury. RESULTS were consistent across different outcome measures of acute injury (ie, fracture or amputations) (N=186), musculoskeletal injury (ie, back strain) (N=137), and serious injury claims (ie, long duration, high cost and/or fatal) (N=155). CONCLUSION: Certification did not reduce the risk of work injury among experienced tree-fallers in the province of British Columbia. Non-statistically significant increases in the observed risk of work injury in the months immediately following certification may be attributable to an intervention effect or a methodological limitation related to a lack of individual-level, time-at-risk exposure data. Language: en

The reuse of Open Source Software (OSS) for safetycritical systems is seen with interest by industries, such as automotive, medical, and aerospace, as it enables shorter time-tomarket and lower development costs. However, safety certification demands to supply evidence about OSS quality, and a gap analysis is needed to assess if the cost to produce certification evidence is worthwhile. This paper presents an empirical study on an open-source RTOS (RTEMS). The study investigates the relationship between software complexity and the effort to achieve a high test coverage, which is one of the most impacting activity for certification. The objective is to figure out if, and to what extent, it is possible to predict such effort preventively, by looking at software complexity metrics. This would enable a preliminary screening and benchmarking of OSS items, supporting strategic decision making. The study shows that combining metrics with classifiers can achieve a good prediction accuracy.

Context Demonstrating compliance of critical systems with safety standards involves providing convincing evidence that the requirements of a standard are adequately met. For large systems, practitioners need to be able to effectively collect, structure, and assess substantial quantities of evidence. Objective This paper aims to provide insights into how practitioners deal with safety evidence management for critical computer-based systems. The information currently available about how this activity is performed in the industry is very limited. Method We conducted a survey to determine practitioners’ perspectives and practices on safety evidence management. A total of 52 practitioners from 15 countries and 11 application domains responded to the survey. The respondents indicated the types of information used as safety evidence, how evidence is structured and assessed, how evidence evolution is addressed, and what challenges are faced in relation to provision of safety evidence. Results Our results indicate that (1) V&V artefacts, requirements specifications, and design specifications are the most frequently used safety evidence types, (2) evidence completeness checking and impact analysis are mostly performed manually at the moment, (3) text-based techniques are used more frequently than graphical notations for evidence structuring, (4) checklists and expert judgement are frequently used for evidence assessment, and (5) significant research effort has been spent on techniques that have seen little adoption in the industry. The main contributions of the survey are to provide an overall and up-to-date understanding of how the industry addresses safety evidence management, and to identify gaps in the state of the art. Conclusion We conclude that (1) V&V plays a major role in safety assurance, (2) the industry will clearly benefit from more tool support for collecting and manipulating safety evidence, and (3) future research on safety evidence management needs to place more emphasis on industrial applications.

Software safety certification involves checking that the software design meets the (software) safety requirements. In practice, inspections are one of the primary vehicles for ensuring that safety requirements are satisfied by the design. Unless the safety-related aspects of the design are clearly delineated, the inspections conducted by safety assessors would have to consider the entire design, although only small fragments of the design may be related to safety. In a model-driven development context, this means that the assessors have to browse through large models, understand them, and identify the safety-related fragments. This is time-consuming and error-prone, specially noting that the assessors are often third-party regulatory bodies who were not involved in the design. To address this problem, we describe in this paper a prototype tool called, SafeSlice, that enables one to automatically extract the safety-related slices (fragments) of design models. The main enabler for our slicing technique is the traceability between the safety requirements and the design, established by following a structured design methodology that we propose. Our work is grounded on SysML, which is being increasingly used for expressing the design of safety-critical systems. We have validated our work through two case studies and a control experiment which we briefly outline in the paper.

This study first focuses on the quantitative evaluation of current indirect regulation on industrial machines and devices in Korea. Statistical analysis of industrial accidents reveals the fact that more efforts must be directed towards securing the essential safety of industrial machines and devices at manufacturing stage hence guaranteeing the effectiveness of the regulation. In order for the regulation to be further effective balanced direct regulation on both manufacturers and users of industrial machines and devices needs to be implemented. An example of such transition is also shown